This application is based on and incorporates herein by reference Japanese Patent Application No. 2001-307881 filed on Oct. 3, 2001.
1. Field of the Invention
The present invention relates to a variable valve timing controller that changes opening and closing timing of intake valves and/or exhaust valves of an internal combustion engine according to operating conditions of the engine. The opening and closing timing is referred to as valve timing, and the internal combustion engine is referred to as an engine hereafter.
2. Description of Related Art
Conventionally, a known vane type variable valve timing controller comprises a vane member that rotates with a camshaft, and a housing member that receives driving force from a crankshaft of an engine. In the vane type variable valve timing controller, the vane member is housed in the housing member so that the vane member is capable of rotating relative to the housing member. The variable valve timing controller controls the valve timing of intake valves and/or exhaust valves of the engine by hydraulically controlling a phase of the vane member relative to that of the housing member, a phase difference resulting from a relative rotation between the crankshaft and the camshaft.
A variable valve timing controller disclosed in Japanese Patent Laid-Open Publication No. 10-110603 (corresponding to U.S. Pat. No. 5,832,887) has a stopper piston housed in a vane member and a ring-shaped member press-fitted in a side wall of a housing member. The stopper piston engages with the ring-shaped member to restrain rotation of the vane member relative to the housing member.
The side wall of the housing member is formed with a through hole to receive a sliding member such as a camshaft that is connected with the vane member and rotates relative to the housing member, or a bushing that rotates with the vane member relative to the housing member. The camshaft or the bushing rotates with the vane member in sliding contact with the inner periphery of the through hole formed in the side wall of the housing member.
If the ring-shaped member for engaging with the stopper piston is press-fitted into the side wall of the housing, stress arises in the side wall around the ring-shaped member and the stress transmits to the through hole, causing deformation of the through hole. If the through hole deforms, sliding friction between the inner periphery of the through hole and the camshaft or the bushing increases. As a result, smoothness of the relative rotation between the housing member and the vane member is deteriorated.
It is therefore an object of the present invention to provide a variable valve timing controller that attains smooth relative rotation between a housing member and a vane member.
According to an aspect of the present invention, a variable valve timing controller is formed with a hole in a side wall of a housing member, wherein a restraining member for receiving a movable member is press-fitted into the hole. The valve timing controller is also formed with a through hole in the center of the side wall of the housing member.
The hole in which the restraining member is press-fitted is formed with a part non-contacting with the restraining member in a state in which the restraining member is press-fitted into the hole. The non-contacting part is a recess extending in an axial direction and is located near the through hole. The restraining member is apart from the inner surface of the hole where the non-contacting part is formed when the restraining member is press-fitted into the hole. Therefore, development of stress at the hole around the non-contacting part, a portion of the hole near the through hole, is minimized when the restraining member is press-fitted into the hole, and deformation of the through hole is inhibited. Accordingly, sliding friction between the inner periphery of the through hole and a sliding member that rotates in sliding contact with the through hole is minimized, and the sliding member smoothly rotates in the side wall of the housing member. As a result, relative rotation between the housing member and the vane member is retained smooth.
According to another aspect of the present invention, a non-contacting part formed in a hole into which a restraining member is press-fitted provides a fluid passage that delivers fluid to apply hydraulic pressure to the movable member in a direction to disengage the movable member from the restraining member.